EFFECTS OF PROSOPIS JULIFLORA (SW)DC ON SOIL SEEDBANK FLORA AND ITS ALLELOPATHIC POTENTIALS ON SELECTED GRASS SPECIES IN AMIBARA RANGELAND OF AFAR REGIONAL STATE, ETHIOPIA

Abstract

P. juliflora is an evergreen exotic poisonous weed species and its alarming rate of invasiveness had affecting the livelihood of pastoral communities in Amibara rangeland of Afar Region. This study aims to investigate effects of P. juliflora on soil seedbank flora and its allelopathic potential on seed germination, growth and biomass production of Cenchrus cillaris, paspalidium desertorum and Litonia nutans. A total of 20 Soil samples were collected from five sites measuring sample quadrats of (20m X 20m) area and soil samples from each quadrat were taken from 5 sub-quadrats/m2, one from center and four from corners, at two depth (0-3cm and 3-10 cm). A total of 38 herbaceous species /m2 that belongs to 16 families were emerged in upper and lower layer soil seedbank samples. The highest diversity of (3.17, 3.15 and 3.04) were recorded in Awash-arba, Alaydagi and Kurkura. While, least diversity of (2.75and 2.77) were recorded in Melka-Werer and Sarkamo. Jaccard’s coefficient similarity of (55.6%) at the upper soil seedbank were in Melka-werer and Sarkamo. while lowest similarity of (31.8%) were recorded at lower layer soil seedbanks in Sarkamo and Kurkura. Ten grams of each leaf, bark and root aqueous extract prepared at (0%, 1%, 2.5%, 5% and 10%) concentrations used for germination bioassay and pot experiment. Seed germination of P.desertorum was significantly inhibited by leaf extract at (42.13). C.cillaris seed germination was significantly suppressed at (2.5%, 5% and 10%) as compared with control. Plumule length (cm) of C. cillaris was highly significantly inhibited at (10%) when compared to control. Radical length of C. Cillaris, P. desertorum and L. nutans were exhibited highly significant inhibition at (5% and10%) when compared to control. Bark exposed highly significant effect on fresh shoot weight of C. cillaris and L. nutans at (10%) and P. desertorum at (5% and 10%), while least significant exhibited at (1%) as compared to control. Bark exposed significant inhibition on dry shoot weight of L. nutans at (9.87). Root exhibited least significant inhibition on dry shoot weight of C. cillaris at (14.91). Bark showed significant reduction on fresh root weight of L.nutans at (6.03). Therefore, out controlling invasion of p. juliflora causing negative impacts on plant diversity, ecosystem services and forage grass species.